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Peak 97, a Climbing Game 


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Peak 97, a Climbing Game 

Written By: Jeff 


I've posted a video of the gameplay to Flickr: 1(5)N07... 

I have been slowly working on a series of automatons and robotic effigies of my coworkers 
as a way to exercise my creativity without cluttering the house with kid-unfriendly creations. 
My two main design criteria were low cost and uniqueness. Builds included a stand-up 
paddle-boarder; a duct-tape speed boat; a soda-can steam-powered jet ski; and a wheeled, 
obstacle-avoiding room-roamer with a cross-country skiing action. For my next trick, I 
thought it would be fun to try something climbing- related. You may have noticed the outdoor 
theme here. I work for REI, a large consumer co-operative charged with inspiring, educating 
and outfitting folks for a lifetime of outdoor adventure. 

I knew it was going to be tricky to build a climber inexpensively. All the climbing bots I could 
find on the web used either magnetic wheels (not authentic enough for me) or enough servos 
to blow my budget ten times over. I thought perhaps I could reach my goal by tweaking the 
leg shapes of a bi-core walker, a popular BEAM design. Some experimentation later, I found 
I could coax a climbing action given a sloped and carpeted surface. I played around with 
carpet-covered sheet metal and super-magnets on the hands and feet, but the sheet metal 
was going to add too much time and cost to the project. I settled on sharp hands and feet 
moving up a carpeted plywood surface, as that perfectly matched the scrap materials I 
already had on hand. 

Unfortunately, mounting batteries was going to be tricky, as the center of gravity was touchy 
enough with just the servos hanging out on the back. Cramming on tiny sensors and 
compact control circuitry also seemed like more work than I wanted to put into this project, 

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Peak 97, a Climbing Game 

especially considering that most of the other creations in this series took less than two 
hours. As such, I moved to a tethered design, but then had to decide how the tethers would 
affect the climbing action. It would be great if the tether hung like a tail, but I couldn't keep 
the climber's arms on the wall with the added weight. 

Having decided that the tethers would be top-ropes, so to speak, the idea struck me that I 
could make a game of it, two climbers racing against each other. After that, it was just a 
matter of implementation and refinement. 

One Arduino reads the pots and controls the climbers' servos while the other Arduino 
handles the game mechanics: power, LCD, timing, music, and win detection. 

The single button turns everything on or off with a Polulu Power Switch. Upon power-up, 
there is a brief title screen, a plea for gentility, and then the countdown begins. When the 
race starts, the control Arduino signals the climber Arduino to start mapping the servos to 
the pots. 

Both climbers use the same three-dollar servos I ordered direct from Hong Kong. One 
climber is significantly longer than the other, but less stable. Rather than perfect each 
climber, I chose to leave them a little rough and hard to handle. In the future, I may add 
obstacles to the climbing wall, but I want to first see how things go with a blank wall. 

My first versions of the sheet aluminum arms and legs terminated in digits crudely shaped 
with oversized tin snips. These held the carpet passably, but threw off the steering. I 
installed tacks in each hand and foot, making a world of difference in grip and control. I 
really wanted the hands to be holding ice axes, as ice axes were the reason for founding 
REI. Unfortunately, the added length messed up the geometry. Perhaps I'll revisit the idea 
when the current climbers break. Yes, I don't expect any of my parts to last long at the 
hands of enthusiastic players. 

Anyway, the spikes are connected to ground, and the wall's aluminum snow caps are each 
connected to a pin on the control Arduino. The winner is announced, either Mary or Lloyd 
(the names of the couple that founded REI), and the elapsed time is displayed. I considered 
storing high scores in the EEPROM, but they wouldn't have meant as much without the 
players' names, and text entry is another thing beyond the scope of this cheap and lazy 
project. As such, the winner has 30 seconds to scribble down their score on a chalkboard or 
tweet a picture of the display hash-tagged #peak97. 

Until we can that pool table in the break room at work, this'll be the next best thing :) 

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Peak 97, a Climbing Game 

Step 1 — Peak 97, a Climbing Game 

• You'll need a carpet-covered 
mountain. I used eighth-inch 
plywood connected by a piano- 
hinge. Be sure to spread the carpet 
glue (I used Liquid Nails) with a 
putty knife so the carpet is 
uniformly secured. I added two 
separate aluminum "snow caps" to 
act as electrical contact points to 
detect which climber wins. 

Step 2 

• The Arduino that reads the pots 
and controls the climbers is in the 
box on the back side, right above 
the 4D battery holder. Add some 
tape to the meeting point of the 
snow caps to keep the wires from 
snagging and to keep the snow 
caps from touching each other. 
Keep the back side of the game as 
neat as possible to avoid snags as 
the climbers climb. 

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Peak 97, a Climbing Game 

Step 3 

• One scratch-built Arduino, a fuse 
holder, a Polulu Power Switch, a 
low-dropout power supply (shared 
by both Arduinos), and a terminal 
strip that eased connections as I 
brought various parts online during 
the build. 

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Peak 97, a Climbing Game 

Step 4 

• Each climber's "rope" consists of 
two twisted pairs stolen from a Cat 
5 network cable. Make sure to get 
the flexible variety that uses 
stranded wire. Otherwise your 
ropes won't get out of the way as 
the climbers climb. 

• Strategically place fishing weights 
to counterweight the climber and 
the amount of wire on the other 
side of the peak. The 3/4 ounce 
weight is for the climber and some 
wire. The inline 1/4 ounce weights 
counteract the initial full load of 
wire, but descend to the other side 
of the droop as the climber climbs 
and less weight is needed. If you 
get the weights wrong, you'll have a 
terrible time keeping all of the 
climbers' hands and feet on the 

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Peak 97, a Climbing Game 

Step 5 

• Each climber consists of two micro 
servos joined by foam tape and 
scraps of plastic. The arms and 
legs are cut and formed from small 
sheets of aluminum, available at 
your local hardware store. 

• You may to build the climbers first, 
as I did. Then you can test various 
slopes for your carpet mountain. 

Step 6 

• You'll want to form the limbs to 
keep the servos as close to the 
wall as possible while still keeping 
the tacks deep into the carpet. 

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Peak 97, a Climbing Game 

Step 7 

• If you want the full gaming 

experience, you'll want to wire the 
hands to ground so that the control 
Arduino can detect which climber 
wins. I tried using a small jumper to 
the aluminum but the hot glue 
holding the tacks in the hands 
wasn't conducting, so I wired the 
tacks directly, then glued them in. 

Step 8 

• The feet don't need to conduct, so 
slop on the glue. 

• Make sure you have the tacks from 
all hands and feet engaging the wall 
evenly and at appropriate angles. 
Problems with the tacks or with 
arm/leg length will make steering 

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Peak 97, a Climbing Game 

Step 9 

• I wanted to mount the control box 
so both players could see it, but 
decided against hanging it out to be 
bumped by passersby. 

• Ensure that it's angled well enough 
for the LCD to be readable without 
leaning back or squatting. 

Step 10 

• The control box is a great place for 
the control Arduino, as it has many 
connections to the LCD. I used the 
$12 LCD from Adafruit, as well as 
one of their piezo buzzers (bottom 
right) for my music. 

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Peak 97, a Climbing Game 

Step 11 

• While I programmed the climber 
Arduino before I even built the 
climbers, I didn't program the 
control Arduino until I had the rest 
of the game assembled. Your 
mileage may vary, as they say. 

• It's time, if you have not yet done 
so, to name your creation and 
consider some theme music and 
other aspects of gameplay. 

• I would have posted my code, but 
it's nothing special, and if you don't 
know offhand how to write such 
things, I guarantee you'll have fun 

Step 12 


B Curious? See my project 
guide at iittp // 



• And lastly, should those out in 
meatspace see your nifty project 
and be inspired to build their own, 
don't forget to slap a custom QR 
code on it, linking to your project 

This document was last generated on 2012-11-03 03:22:38 AM. 

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